Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

{ 
  Das akzeptierte Format von StrToDate und StrToTime wird in den globalen Variablen 
  DateSeparator und ShortDateFormat definiert. 

  The accepted format of StrToDate and StrToTime is defined in the global 
  variables DateSeparator and ShortDateFormat 
}

 function IsDate(str: string): Boolean;
 var
   dt: TDateTime;
 begin
   Result := True;
   try
     dt := StrToDate(str);
   except
     Result := False;
   end;
 end;

 function IsTime(str: string): Boolean;
 var
   dt: TDateTime;
 begin
   Result := True;
   try
     dt := StrToTime(str);
   except
     Result := False;
   end;
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 begin
   if IsDate('24.07.2001') then
   begin
     ShowMessage('Yes, it is a date.');
   end;

   if IsTime('16:23') then
   begin
     ShowMessage('Yes, it is a time.');
   end;
 end;